1. Field of the Invention
The present invention relates to a compound, a scintillator, and a radiation detector.
2. Description of the Related Art
Radiation detectors used for radiodiagnosis are configured to detect applied radiation in order to acquire radiographs as digital signals. The radiation detectors are broadly divided into direct radiation detectors and indirect radiation detectors. An indirect radiation detector is a detector that acquires an image by changing radiation into visible light with a scintillator composed of a phosphor, allowing the visible light to be received on a photoelectric conversion element, for example, a photodiode composed of amorphous silicon (a-Si), a photodiode composed of single-crystal silicon (c-Si), or a charge-coupled device (CCD), and converting the visible light into a charge signal.
In the case where a-Si is used as a photoelectric conversion element for an indirect radiation detector, a-Si has sensitivity in a wavelength band of 450 nm to 650 nm; hence, a scintillator is required to exhibit light emission in a wavelength band of about 450 nm to about 650 nm. In the case where c-Si is used as a photoelectric conversion element, c-Si has sensitivity in the region of longer wavelengths than a-Si, i.e., in the region of about 500 nm to about 900 nm; hence, a scintillator is required to exhibit light emission in a wavelength region corresponding to the region.
Japanese Patent Laid-Open No. 2003-147343 discloses a scintillator composed of a mixed crystal of cesium iodide and copper iodide. The patent document states that the mixed crystal contains a Cs3Cu2I5 compound and exhibits light emission at a wavelength of about 440 nm. Unfortunately, the emission wavelength range of the mixed crystal described in the patent document differs from a wavelength band suitable for the sensitivity characteristics of a photoelectric conversion element (a-Si or c-Si). Thus, the intensity when light emitted from the mixed crystal is received on the photoelectric conversion element (the intensity of light received) is not sufficient. Accordingly, aspects of the present invention provide a novel compound in which when light emitted from the compound is received on a photoelectric conversion element, the intensity of the light received is higher than those of the related art.